Display apparatus using electroluminscence elements and method of manufacturing the same

ABSTRACT

A display apparatus having electroluminescense (EL) elements includes a light emitting layer for generating light. A high energy laser beam is irradiated on the luminous element layer to define a plurality of regions of the light emitting layer. A plurality of first electrodes are arranged generally parallel to each other over a first surface of the light emitting layer and a plurality of second electrodes are arranged generally parallel to one another and perpendicular to the first electrodes on a second, opposite surface of the light emitting. The EL elements are formed at the intersections of the first and second electrodes.

This application is a divisional of application Ser. No. 08/987,460filed on Dec. 9, 1997 now U.S. Pat. No. 6,114,183.

BACKGROUND OF THE INVENTION

The present invention relates to a display apparatus usingelectroluminescence elements, and a method of manufacturing the displayapparatus.

Electroluminescence (EL) elements for use in a display apparatus includean inorganic EL element and an organic EL element. The inorganic ELelement uses a thin film of an inorganic compound, like zinc selenide orzinc sulfide, as a fluorescent material, and the organic EL element usesan organic compound as a fluorescent material. Preferably, the organicEL element has the following features:

(1) A high external quantum efficiency.

(2) Light is emitted on a low driving voltage.

(3) Multifarious colors (green, red, blue, yellow, etc.) can begenerated by selecting a proper fluorescent material.

(4) The display is clear and no back light is needed.

(5) There is no dependency on the viewing angle.

(6) The organic EL element is thin and light.

(7) A soft material like a plastic film can be used for the substrate.

Due to the aforementioned features, a display apparatus using such anorganic EL elements (hereinafter referred to as “organic EL displayapparatus”) is a desirable replacement for a CRT or liquid crystaldisplay.

An organic EL display apparatus employs a dot matrix system whichdisplays an image with dots arranged in a matrix form. The dot matrixsystem includes a simple matrix system or an active matrix system.

The simple matrix system directly drives organic EL elements of a matrixof pixels, arranged on a display panel, in synchronism with a scansignal using an external driving unit. Each pixel on the display panelhas only an organic EL element. As the number of scan lines of a displayapparatus increases, therefore, the driving time (duty) assigned to eachpixel decreases. This reduces the contrast as well as the luminanceintensity of the display screen.

In the active matrix system, each of pixels arranged in a matrix formhas an organic EL element and a pixel driving element (active elements).The pixel driving element serves as a switch which is switched on or offby the scan signal. A data signal (display signal, video signal) istransmitted to the anode of the associated organic EL element via anenabled pixel driving element. As the data signal is written in theorganic EL element, the organic EL element is driven. Even when thepixel driving element is switch off state, the data signal previouslyapplied to the anode of the organic EL element is held, in the form of acharge, in the organic EL element. The organic EL element is kept drivenuntil the associated pixel driving element is switched on again. Even ifthe driving time per pixel driving element decreases as the number ofscan lines is increased, therefore, the driving of the organic ELelements is not affected. Specifically, a sufficient luminance intensityis secured for an image to be displayed on the display panel andreduction in the contrast is prevented. The active matrix system cantherefore provide display images with a higher quality than the simplematrix system.

Depending on the difference in pixel driving elements, displayapparatuses of the active matrix system are classified into a transistortype (three-terminal type) and a diode type (two-terminal type). Thetransistor type is more difficult to manufacture than the diode type. Onthe other hand, the contrast and resolution of images which aredisplayed by the transistor type display apparatus can be improvedeasily. Therefore, the transistor type display apparatus provideshigh-quality images which match with those displayed by a CRT display.The following description on the operational principle of the activematrix system is mainly associated with the transistor type.

A conventional organic EL display apparatus 101 of the simple matrixsystem will now be discussed with reference to FIGS. 1 through 3.

As shown in FIG. 1, a plurality of anodes 103 are arranged, parallel toone another, on an insulator substrate 102, and a light emitting layer104 is provided on the insulator substrate 102 to cover the anodes 103.A plurality of cathodes 105 are arranged, parallel to one another, onthe light emitting layer 104. The anodes 103 are placed perpendicular tothe cathodes 105. The light emitting layer 104, the anodes 103 and thecathodes 105 form an organic EL element 106. The insulator substrate 102is preferably made of transparent glass, synthetic resin or the like.The anodes 103 are preferably formed of transparent electrodes of ITO(Indium Tin Oxide) or the like. The light emitting layer 104 ispreferably formed of an organic compound. The cathodes 105 arepreferably formed of a magnesium-indium alloy.

In the organic EL element 106, holes coming from the anodes 103 arerecombined with electrons coming from the cathodes 105 inside the lightemitting layer 104, emitting light. The light is emitted outside via theanodes 103 and the transparent insulator substrate 102 as indicated bythe arrow γ in FIG. 2.

FIG. 3 is a schematic plan view of the organic EL display apparatus 101,as viewed from the anodes 103. In FIG. 3, only the anodes 103 and thecathodes 105 are illustrated.

Defined at the individual intersections of anodes 103 a to 103 c andcathodes 105 a to 105 c are light emitting areas B1 to B9 which emitlight, as discussed above. That is, the light emitting areas B1-B9,arranged in a matrix form, form the organic EL display apparatus 101.

In the simple matrix system, the positive terminal of a driving powersupply is connected to one anode 103, and the negative terminal of thedriving power supply is connected to the corresponding cathode 105. Inthis manner, the anode 103 and the cathode 105 are energized.

In order for light emitting area B2 at the intersection of the anode 103b and the cathode 105 a to emit light, for example, the positiveterminal is connected to the anode 103 b and the negative terminal isconnected to the cathode 105 a, and power is supplied through theterminals. As a result, a forward current flows, as indicated by thearrow α.

Since the light emitting layer 104 is provided on the insulatorsubstrate 102 so as to cover a plurality of anodes 103, a leak currentflows, as indicated by the arrow β. The leak current energizes not onlythe light emitting area B2, but also the light emitting areas B1, B3 andB5 near the light emitting area B2. As a result, the light emittingareas B1, B3 and B5 emit light. This phenomenon is called an opticalcrosstalk caused by the leak current characteristic of the EL element106. This shortcoming is inherent not only to the simple matrix systembut also to the active matrix system and occurs in an inorganic ELdisplay apparatus as well as an organic EL display apparatus.

The optical crosstalk deteriorates the contrast of images displayed bythe organic EL display apparatus 101, disabling the acquisition ofhigh-definition images. Particularly, a full-color organic EL displayapparatus using EL elements causes color “smearing” and does not provideclear images.

Japanese Unexamined Patent Publication No. Hei 4-249095 discloses an ELelement which prevents the occurrence of such a crosstalk as a solutionto the aforementioned problem. In the EL element, a plurality of lightemitting elements each comprised of an organic compound are providedapart from one another between a transparent electrode and a pluralityof metal electrodes. Since the individual light emitting elements in theEL element are provided apart from one another, a crosstalk originatingfrom the leak current does not occur. This makes an image to bedisplayed clearer.

As light emitting elements are made of an organic compound, they havepoor water resistance. Therefore, the photolithography technology whichuses cleaning water cannot be used in separating light emittingelements. The individual EL elements are thus formed directly using ametal mask. The use of the metal mask restricts the micro work of lightemitting elements and gets in the way of improving the clearness ofdisplay images.

Accordingly, it is an object of the present invention to provide adisplay apparatus capable of displaying clear images and a method ofmanufacturing the same.

SUMMARY OF THE INVENTION

Briefly stated, the present invention provides a method of manufacturinga display apparatus, comprising the steps of: providing a light emittinglayer for generating light; and irradiating a high-energy beam on saidlight emitting layer to define said light emitting layer into aplurality of regions.

The present invention further provides a method of manufacturing adisplay apparatus, comprising the steps of: providing a plurality offirst electrodes generally parallel to one another; forming a lightemitting layer for generating light on said first electrodes;irradiating said light emitting layer with a high-energy beam to definesaid light emitting layer into a plurality of regions; and forming asecond electrode on said defined regions of said light emitting layer.

The present invention provides a method of manufacturing a displayapparatus comprising the steps of: providing a plurality of firstelectrodes which extends generally parallel to one another; forming alight emitting layer of an organic compound for generating light on saidfirst electrodes; irradiating said light emitting layer with a laserbeam to define said light emitting layer into a plurality of regions;and forming a plurality of second electrodes on said defined regions ofsaid light emitting layer which extend generally parallel to one anotherand generally perpendicular to said first electrodes.

The present invention further provides a display apparatus of an activematrix system comprising: a light emitting layer having a first surfaceand a second surface opposite to said first surface and defined into aplurality of regions; a plurality of first electrodes arranged,generally parallel to one another, over said first surface of said lightemitting layer; a plurality of second electrodes arranged, generallyparallel to one another and intersecting said first electrodes, oversaid second surface of said light emitting layer; electroluminescenceelements formed at individual intersections of said first electrodes andsaid second electrodes; and driving elements, arranged in associationwith said electroluminescence elements, for driving the associatedelectroluminescence elements.

Other aspects and advantages of the invention will become apparent fromthe following description, taken in conjunction with the accompanyingdrawings, illustrating by way of example the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings.

FIG. 1 is a perspective view showing a conventional organic EL displayapparatus;

FIG. 2 is a cross-sectional view taken along the line 2—2 in FIG. 1;

FIG. 3 is a plan view showing only the electrodes of the displayapparatus of FIG. 1;

FIG. 4 is a perspective view of an organic EL display apparatusaccording to a first embodiment of the invention;

FIG. 5 is a schematic diagram illustrating a manufacturing step of thedisplay apparatus of FIG. 4;

FIG. 6A is a cross-sectional view of the display apparatus showing afirst manufacturing step;

FIG. 6B is a cross-sectional view of the display apparatus showing asecond manufacturing step;

FIG. 6C is a cross-sectional view of the display apparatus taken alongthe line 4 c—4 c in FIG. 4, showing a third manufacturing step;

FIG. 7 is a cross-sectional view of an organic EL display apparatusaccording to a second embodiment of the present invention;

FIG. 8 is a cross-sectional view of an organic EL display apparatusaccording to a third embodiment of the present invention;

FIG. 9 is a block diagram illustrating the organic EL display apparatusof FIG. 8; and

FIG. 10 is a schematic circuit diagram of an equivalent circuit showinga pixel of the organic EL display apparatus of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawing, like numerals are used for like elements throughout.

First Embodiment

A display apparatus according to the first embodiment of the presentinvention will now be described with reference to FIGS. 4 through 6.

As shown in FIG. 4, an organic EL display apparatus 11 of the simplematrix system includes a transparent insulator substrate 12 of glass ora synthetic resin. A plurality of anodes 13 are formed generallyparallel to one another on the substrate 12. The anodes 13 are formed oftransparent electrodes preferably of ITO (Indium Tin Oxide). Lightemitting layers 14 of an organic compound are respectively formed on theanodes 13.

A passivation layer 15 preferably made of SOG (Spin On Glass), islocated in each space on the insulator substrate 12 between theadjoining light emitting layers 14. The individual passivation layers 15define the light emitting layers 14 and isolate adjacent light emittinglayers 14.

A plurality of band-like cathodes 16 of a magnesium-indium alloy areformed on the passivation layers 15 and the light emitting layers 14 andextend generally parallel to one another. The individual cathodes 16extend in a direction generally perpendicular to the anodes 13, thelight emitting layers 14 and the passivation layers 15. An organic,ELelement 17 comprises the light emitting layers 14, the anodes 13 and thecathodes 16.

The manufacturing process of the organic EL display apparatus 11 willnow be described.

As shown in FIG. 6A, the individual anodes 13 are formed on theinsulator substrate 12, preferably by using sputtering, electron beamvapor deposition, atmospheric thermal CVD, spraying, dipping or plasmaCVD. The light emitting layers 14 are formed on the insulator substrate12 to cover the individual anodes 13 using electron beam vapordeposition. It is preferable that the anodes 13 to have a uniformthickness.

Then, a high-energy laser beam is irradiated such that a first portionof the light emitting layer 14 is located on each associated anode 13and a second portion of the light emitting layer 14, excluding the firstportion, is removed, as shown in FIG. 6B. As a result, the secondportion of each light emitting layer 14 is removed, leaving the firstportion of the light emitting layer 14 on the associated anode 13. Thelight emitting layers 14 on the respective anodes 13 are thus formed,preferably substantially parallel to one another, along the anodes 13.

The laser beam is irradiated as shown in FIG. 5. The laser beam, emittedfrom a laser device 21, enters a beam expander 22. In this embodiment, aKrF excimer laser having a wavelength of 248 nm is used. The laser beamhas an irradiation area of 10 mm×10 mm and energy of 600 mJ/cm². Thelaser beam is not limited to this particular one. For example, an ArFexcimer laser with a wavelength of 193 nm, XeCl excimer laser with awavelength of 308 nm, XeF excimer laser with a wavelength of 351 nm,copper vapor laser with a wavelength of 578 nm, Ar laser with awavelength of 515 nm, the second harmonic of a YAG laser with awavelength of 530 nm, or the like may be used as well. The lightemitting layers 14 may be scanned with a laser beam directly to beremoved or reformed without using the beam expander 22. To implement auniform work, it is desirable to use a laser beam which has a certain,constant energy distribution characteristic. Further, an electron beamor ion-beam may be used in place of a high-energy laser beam.

The laser beam incident to the beam expander 22 is enlarged in the formof a thin slit, which increases the irradiation area of the laser beam.The beam expander 22 preferably comprises a pair of cylindrical lenses.The energy of the enlarged laser beam ranges from 10 to 500 mJ/cm². Asthe laser beam hits the second portion of each light emitting layer 14between the anodes 13, the second portion is linearly and collectivelyremoved.

Then, the passivation layer 15, preferably of SOG, is formed between theadjoining light emitting layers 14, as shown in FIG. 6C. Then, theelectrode layer, preferably of a magnesium-indium alloy, is formeduniformly and in a uniform thickness on the passivation layers 15 andthe light emitting layers 14 preferably by electron beam vapordeposition. The electrode layer is cut by the aforementioned laser beamto form a plurality of cathodes 16, which run generally perpendicular tothe anodes 13.

In the organic EL element 17 with the above-described structure, theholes coming from each anode 13 are recombined with the electrons comingfrom the associated cathode 16 inside the associated light emittinglayer 14, and light is emitted outside from the transparent anode 13 viathe transparent substrate 12. At this time, each light emitting layer 14is defined and isolated by the passivation layers 15 so that no leakcurrent flows from one light emitting layer 14 to another, whichprevents the occurrence of a crosstalk and improves the clearness ofdisplayed images.

The present embodiment uses a laser beam to define the light emittinglayers 14. The use of the laser beam facilitates the manufacturingprocess of the organic EL element 17 which is free of a crosstalk.Further, the use of the laser beam permits the fine removal of thesecond portions of the light emitting layers 14. Such micro work allowsthe organic EL element 17 having a high resolution to be manufactured.

Second Embodiment

The second embodiment of this invention will be discussed belowreferring to FIG. 7.

In an organic EL display apparatus 25 according to the secondembodiment, after a plurality of anodes 13 are formed on an insulatorsubstrate 12, a light emitting layer 14 having a uniform thickness isformed on the substrate 12 to cover the anodes 13. A high-energy laserbeam is locally irradiated on (second) portions of the light emittinglayer 14, excluding first portions thereof on the anodes 13. Theirradiated second portions are reformed to high-resistance portions 14 aby the heat. The light emitting layer 14 is thus defined into aplurality of areas by the high-resistance portions 14 a. In other words,the high-resistance portions 14 a define the light emitting layer 14 onthe associated anodes 13.

Then, a plurality of cathodes 16 are formed generally perpendicular tothe anodes 13 on the light emitting layer 14 and the high-resistanceportions 14 a.

In the organic EL display apparatus 25 of the second embodiment, as perthe first embodiment, the light generated by the light emitting layer 14goes outside through the anodes 13 and the substrate 12. At this time,since the high-resistance portions 14 a define the light emitting layer14 on the respective anodes 13, no leak current flows from one portionof the light emitting layer 14 to another, which prevents the occurrenceof crosstalk and leads to an improvement on the clearness of displayedimages.

Third Embodiment

A third embodiment of the present invention will be discussed below withreference to FIGS. 8 through 10.

As shown in FIG. 8, each pixel 32 of an organic EL display apparatus 31of the active matrix system has a thin film transistor (TFT) 33 as apixel driving element. The TFT 33 is a planar type, and has an activelayer comprised of a polycrystalline silicon film 34. The TFT 33preferably has an LDD (Lightly Doped Drain) structure. Thepolycrystalline silicon film 34 is formed on an insulator substrate 12.A gate insulator film 35 is formed on the polycrystalline silicon film34, with a gate electrode 36 formed on the gate insulator film 35.Defined on the polycrystalline silicon film 34 are a high-concentrationdrain region 37 a, a low-concentration drain region 37 b, ahigh-concentration source region 38 a and a low-concentration sourceregion 38 b.

An interlayer insulator film 39 is formed on the TFTs 33. Thehigh-concentration drain region 37 a is connected to a drain electrode41 via a contact hole 40 formed in the interlayer insulator film 39. Thehigh-concentration source region 38 a is connected to a source electrode43 via a contact hole 42 formed in the interlayer insulator film 39.

A planarizating insulator film 44 is formed on the individual electrodes41 and 43 and the interlayer insulator film 39. The source electrode 43is connected to the associated anode 13 via a contact hole 45 formed inthe planarizating insulator film 44.

Each of the insulator films 35 and 39 is preferably comprises a siliconoxide film, silicon nitride film or a silicon nitride oxide film. Theplanarizating insulator film 44 is preferably comprised of a siliconoxide film, a silicon nitride film, a silicon nitride oxide film, asilicate glass film, a SOG (Spin On Glass) film or a synthetic resinfilm (like a polyimide-based resin film, organic silica film or acrylicresin film). The electrodes 41 and 43 preferably comprise an aluminumalloy film.

A light emitting layer 14 is formed on the flattening insulator film 44.The light emitting layer 14 includes a first hole transporting layer 50,a second hole transporting layer 51, a light emitting layer 52 and anelectron transporting layer 53. The layers 50-53 are preferablylaminated, in order, on the insulator film 44. The first holetransporting layer 50 is preferably formed of MTDATA(4,4′,4″-tris(3-methylphenylphenylamino)triphenyl amine). The secondhole transporting layer 51 is preferably formed of TPD(4,4′-bis(3-methylphenylphenylamino)biphenyl). The light emitting layer52 is preferably formed of BeBq2 (10-benzo[h]quinolinol-berylliumcomplex) containing a quinacridone derivative. The electron transportinglayer 53 is preferably formed of BeBq2. The individual layers 50-53, theanodes 13 and the cathodes 16 form an organic EL element 17.

In the organic EL element 17 according to the third embodiment, holesand electrons are recombined inside the light emitting layer 52,generating light. The light goes outside via the anodes 13 and theinsulator substrate 12.

The hole transporting layers 50 and 51 both facilitate the injection ofthe holes from the anodes 13. The electron transporting layer 53facilitate the injection of the electrons from the cathodes 16.

According to the third embodiment, as apparent from the above, theorganic EL element 17 emits green light and has a high external quantumefficiency. A display panel 46 comprised of the organic EL element 17has an improved luminous intensity.

The color of light emitted by the organic EL element 17 varies dependingon the property of the organic compound that forms the light emittinglayer 52. It is preferable that OXD (oxadiazole) or AZM (azomethane-zinccomplex) should be used for the emission of blue light, PYR (pyrazoline)is used for the emission of blue green light, Znq2 (8-quinolinol-zinccomplex) should be used for the emission of yellow light, and ZnPr(porphyrin-zinc complex) should be used for the emission of red light.

Referring now to FIG. 9, the circuit of the organic EL display apparatus31 according to the third embodiment will be described. As shown, theorganic EL display apparatus 31 includes the display panel 46, a gatedriver 55, and a drain driver (data driver) 56.

The display panel 46 has a plurality of gate lines (scan lines) Gl, . .. , Gn, Gn+1, . . . , and Gm, a plurality of drain lines (data lines)Dl, . . . , Dn, Dn+1, . . . , and Dm. The gate lines Gl-Gmperpendicularly cross the respective drain lines Dl-Dm, with pixels 32located at the individual intersections. That is, the pixels 32 on thedisplay panel 46 are arranged in a matrix form.

The gate driver 55, connected to the individual gate lines Gl-Gm,applies a gate signal (scan signal) to the gate lines Gl-Gm. The draindriver 56, connected to the individual drain lines Dl-Dm, applies a datasignal thereto. The drivers 55 and 56 comprise a peripheral drivingcircuit 57. Each of the gate lines Gl-Gm is comprised of the gateelectrode 36 of each TFT 33. Each of the drain lines Dl-Dm is comprisedof the drain electrode 41 of each TFT 33.

FIG. 10 shows an equivalent circuit diagram of the pixel 32. A constantvoltage Vcom is applied to the cathodes 16 of the organic EL element 17,which acts as a capacitor. When a positive voltage is applied to thegate electrode 36 of the TFT 33 with a positive voltage applied to thegate line Gn, the TFT 33 is turned on. As a result, the capacitor of theorganic EL element 17 is charged with a data signal applied to the drainline Dn, so that the data signal is written in the pixel 32. The organicEL element 17 is driven by the data signal.

When a negative voltage is applied to the gate electrode 36 of the TFT33 by a negative voltage applied to the gate line Gn, the TFT 33 isturned off. At this time, the data signal, applied to the drain line Dn,is held in the form of a charge in the capacitor of the organic ELelement 17. In this manner, an arbitrary data signal is held in eachpixel 32 by inputting the data signal to each of the drain lines Dl-Dmand controlling the voltage of each of the gate lines Gl-Gm. The drivingof the organic EL element 17 is maintained by the discharging of thecapacitor until the TFT 33 is turned on again.

As mentioned in the “BACKGROUND OF THE INVENTION”, when the number ofgate lines (scan lines) is increased, the driving time assigned to onepixel 32 becomes shorter. According to the third embodiment, however,since a charge is stored between the anodes 13 and cathodes 16, lightemission is not interrupted, which prevents the contrast of an image tobe displayed on the display panel 46 from decreasing. The organic ELdisplay apparatus 31 of the active matrix system can, therefore, ensurehigher quality display than the organic EL display apparatus of thesimple matrix system.

In the third embodiment, each TFT 33 has an active layer comprised ofthe polycrystalline silicon film 34 and is formed into an LDD structure.It is therefore possible to increase the ON/OFF ratio of the TFT 33 andsuppress the leak current in the OFF state, which leads to an improvedquality of display images.

According to the third embodiment, the high-concentration source region38 a is connected to the associated anode 13 via the source electrode 43in order to provide a good ohmic contact between the high-concentrationsource region 38 a and the anode 13. If the source electrode 43 isomitted, the high-concentration source region 38 a, comprised of thepolycrystalline silicon film 34, is directly connected to the anode 13of ITO. Consequently, the hetero junction of the high-concentrationsource region 38 a and the associated anode 13 generates an energy gapassociated with the band gap difference. Naturally, a good ohmic contactcannot be provided. Unless there is a good ohmic contact between thehigh-concentration source region 38 a and the associated anode 13, thedata signal applied to any of the drain lines Dl-Dm cannot accurately bewritten in the associated pixel 42, which lowers the image quality ofthe organic EL display apparatus 31.

The drain regions 37 a and 37 b may be called source regions, and thedrain electrode 41 may be called a source electrode, in accordance withthe type of the TFT 33 (P-type or N-type). In this case, the drain linesDl-Dm are called source lines, and the drain driver 56 a source driver.

According to the third embodiment, either the first hole transportinglayer 50 or the second hole transporting layer 51 may be omitted, orboth may be omitted. Alternatively, the electron transporting layer 53may be omitted. The present invention can also be adapted to an organicEL element which has any of the aforedescribed element structures.

The TFT 33 may be replaced with a TFT which has an SD (Single Drain)structure or a double gate structure, instead of the LDD structure.Further, the TFT 33 may be replaced with a TFT of a reversed planartype, a staggered type or a reverse staggered type, in place of theplanar type. Furthermore, the TFT 33 may have an active layer which iscomprised of an amorphous silicon film.

It should be apparent to those skilled in the art that the presentinvention may be embodied in many other specific forms without departingfrom the spirit or scope of the invention. Particularly, it should beunderstood that the invention may be embodied in the following forms.

(1) The present invention may be embodied in an organic EL displayapparatus which has a plurality of anodes and one cathode. In this case,the single cathode may have a band-like shape or a planar shape whosearea corresponds to the area of all of the anodes. Further, the presentinvention may be embodied in an organic EL display apparatus which hasone anode and a plurality of cathodes. In this case, the single anodemay have a band-like shape or a planar shape whose area corresponds tothe area of all the cathodes. In any of the aforementioned structures,after a plurality of electrodes (cathodes or anodes) are formed on theinsulator substrate 12, the electrodes are separated by a laser beam.After the light emitting layer 14 is formed on the electrodes, oneelectrode (anode or cathode) is formed on the light emitting layer 14.

(2) The present invention may be adapted to a transistor type organic ELdisplay apparatus of the active matrix system, which uses bulktransistors as pixel driving elements, or a diode type organic ELdisplay apparatus of the active matrix system. Diode type pixel drivingelements include an MIM (Metal Insulator Metal) diode, ZnO (Zinc Oxide)varistor, MSI (Metal Semi-Insulator) diode, BTB (Back to Back) diode andRD (Ring Diode).

(3) Further, the present invention may be adapted to a display apparatuswhich uses inorganic EL elements.

(4) A plurality of light emitting layers 14 may be defined to runperpendicular to the individual anodes 13. Parts of the light emittinglayers 14 which are sandwiched between the individual anodes 13 and theassociated cathodes 16 may be defined or arranged in a matrix form. Thematrix arrangement prevents the occurrence of a crosstalk.

Therefore, the present examples and embodiments are to be considered asillustrative and not restrictive and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalence of the appended claims.

What is claimed is:
 1. A display apparatus of an active matrix system comprising: a light emitting layer having a first surface and a second surface opposite to said first surface and arranged in a matrix form; a plurality of first electrodes opposing said first surface of said light emitting layer; a single second electrode opposing said second surface of said light emitting layer, wherein electroluminescence elements are formed at individual intersections of said first electrodes and said second electrode; and driving elements, arranged in association with said electroluminescence elements, for driving the associated electroluminescence elements.
 2. The display apparatus according to claim 1, wherein said second electrode has a planar shape.
 3. The display apparatus according to claim 1, wherein said driving elements comprise thin film transistors.
 4. The display apparatus according to claim 1, wherein said light emitting layer comprises an organic compound.
 5. The display apparatus according to claim 1, wherein said light emitting layer includes a first hole transporting layer of MTDATA, a second hole transporting layer of TPD, located on said first hole transporting layer, a light emitting layer of Bebq2 containing a quinacridone derivative, and an electron transporting layer of Bebq2 located on said light emitting layer, wherein said second electrode comprises a magnesium-indium alloy.
 6. The display apparatus according to claim 1, wherein said light emitting layer includes a light emitting layer, and at least a hole transporting layer or an electron transporting layer, located on said light emitting layer.
 7. The display apparatus according to claim 6, wherein said hole transporting layer comprises a first hole transporting layer and a second hole transporting layer.
 8. The display apparatus according to claim 1, further comprising an insulating layer arranged in the light emitting layer.
 9. The display apparatus according to claim 1, further comprising high-resistance portions arranged in the light emitting layer.
 10. The display apparatus according to claim 1, wherein the light emitting layer includes a layer for emitting light.
 11. The display apparatus according to claim 1, wherein an area of said second electrode substantially corresponds to areas of all of said first electrodes.
 12. The display apparatus according to claim 1, wherein said second electrode has a planar shape that substantially covers all of said second surface of said light emitting layer.
 13. A display apparatus of an active matrix system comprising: a light emitting layer having a first surface and a second surface opposite to said first surface and defined into a plurality of regions; a plurality of first electrodes opposing said first surface of said light emitting layer; a single second electrode opposing said second surface of said light emitting layer, wherein electroluminescence elements are formed at individual intersections of said first electrodes and said second electrode; and driving elements, arranged in association with said electroluminescence elements, for driving the associated electroluminescence elements.
 14. The display apparatus according to claim 13, wherein said second electrode has a planar shape.
 15. The display apparatus according to claim 13, wherein said driving elements comprise thin film transistors.
 16. The display apparatus according to claim 13, wherein said light emitting layer comprises an organic compound.
 17. The display apparatus according to claim 13, wherein said light emitting layer includes a first hole transporting layer of MTDATA, a second hole transporting layer of TPD, located on said first hole transporting layer, a light emitting layer of Bebq2 containing a quinacridone derivative, and an electron transporting layer of Bebq2 located on said light emitting layer, wherein said second electrode comprises a magnesium-indium alloy.
 18. The display apparatus according to claim 13, wherein said light emitting layer includes a light emitting layer, and at least a hole transporting layer or an electron transporting layer, located on said light emitting layer.
 19. The display apparatus according to claim 18, wherein said hole transporting layer comprises a first hole transporting layer and a second hole transporting layer.
 20. The display apparatus according to claim 13, further comprising an insulating layer arranged in a plurality of regions of the light emitting layer.
 21. The display apparatus according to claim 13, further comprising high-resistance portions arranged in a plurality of second regions excluding the plurality of regions of the light emitting layer.
 22. The display apparatus according to claim 13, wherein the light emitting layer includes a layer for emitting light.
 23. A display apparatus of an active matrix system comprising: a light emitting layer having a first surface and a second surface opposite to said first surface and arranged in a matrix form; a plurality of first electrodes opposing said first surface of said light emitting layer; a single second electrode opposing said second surface of said light emitting layer and used in common to said first electrodes, wherein electroluminescence elements are formed at individual intersections of said first electrodes and said second electrode; and driving elements, arranged in association with said electroluminescence elements, for driving the associated electroluminescence elements.
 24. The display apparatus according to claim 23, wherein said second electrode has a planar shape.
 25. The display apparatus according to claim 23, wherein said driving elements comprise thin film transistors.
 26. The display apparatus according to claim 23, wherein said light emitting layer comprises an organic compound.
 27. The display apparatus according to claim 23, wherein the light emitting layer includes a layer for emitting light.
 28. A display apparatus of an active matrix system comprising: a light emitting layer having a first surface and a second surface opposite to said first surface and defined into a plurality of regions; a plurality of first electrodes opposing said first surface of said light emitting layer; a single second electrode opposing said second surface of said light emitting layer and used in common to said first electrodes, wherein electroluminescence elements are formed at individual intersections of said first electrodes and said second electrode; and driving elements, arranged in association with said electroluminescence elements, for driving the associated electroluminescence elements.
 29. The display apparatus according to claim 28, wherein said second electrode has a planar shape.
 30. The display apparatus according to claim 28, wherein said driving elements comprise thin film transistors.
 31. The display apparatus according to claim 28, wherein said light emitting layer comprises an organic compound.
 32. The display apparatus according to claim 28, wherein the light emitting layer includes a layer for emitting light.
 33. The display apparatus according to claim 13, wherein an area of said second electrode substantially corresponds to areas of all of said first electrodes.
 34. The display apparatus according to claim 13, wherein said second electrode has a planar shape that substantially covers all of said second surface of said light emitting layer. 